As is well known, in the aircraft engine art, bolts used as borescope plugs, drain fittings, chip detectors and the like are secured into place by a variety of positive type locking devices. As for example, bolts can be secured with lockwire, tab washers, threaded inserts and the like. Such devices are in some instances unreliable and in some others impractical or impossible to use.
I have found that I can obviate the problems noted above by utilizing a snap or split ring as the self-locking feature and judiciously locating a land on the shank of the bolt that requires the snap ring to be expanded, by the removal of the bolt, a predetermined torque before the bolt can be retracted fully.